The present invention relates to a wireless communications; and, more particularly, a method for transmitting multimedia wireless data to a host system by using a radio frequency or infrared transmitter.
Data entry devices such as keyboard and mouse are widely being used in inputting data to a host system. In general, both of the keyboard and the mouse are connected to the host system via a cable. When an alphanumeric key on the keyboard or a button on the mouse are pressed by an user, a corresponding key code or a corresponding button code are generated to be transmitted to the host system through the cable. In the host computer, each received code is decoded into its corresponding value, the value being assigned with a specific function for the host system to perform.
As a result of the host system and the data entry devices being connected by the cable, key or button data can be transferred to the host system without entailing any loss of data. Unfortunately, however, the use of cable, in addition to being cumbersome, limits the placement of the data entry devices with respect to the host system to its length.
Accordingly, a wireless data communication between the data entry devices and the host system has been proposed utilizing electromagnetic waves or infra-reds(IR). However, in comparison with the prior art data entry devices using the cable, the data entry devices using the wireless communication are saddled with a relatively slow data communication speed and a low degree of reliability.
FIG. 1 shows a conventional wireless data entry device for transmitting wireless data to a host system 50, which includes a key matrix circuit 10, a microprocessor 20, an infrared(IR) transmitter 30, a pointing device 40 with a position detection unit 41 and a button detection unit 42. The microprocessor 20 continuously scans the key matrix circuit 10 to check whether or not a key has been pressed; if pressed, seeks a keyboard scan code corresponding to the pressed key; converts the same into a predetermined format of serial data(hereinafter called a system scan code) adapted for the host system 50; and transmits it to the host system 50 using the IR transmitter 30. The IR transmitter 30, which incorporates more than one light emitting diode(LED) therein, receives the system scan code from the microprocessor 20, emits IR data corresponding thereto to a receiving unit(not shown) of the host system 50.
The data transmission format used in the conventional device includes four blocks of a header H, a status code S, data D and a check sum C. The header H is the data for indicating to the host system 50 a start of the IR data transmission. The check sum C is used in checking for a data loss which may occur during the transmission. The data D includes eight bits of data, seven bits of which defining the key codes and one bit of which defining the On/Off codes.
The On code is the code which is transmitted when a key is pressed and the Off code is the code which is transmitted when the key is released. In general, since the total number of the keys on the keyboard is about 110 at maximum, all of the key data on the keyboard can be expressed with eight bits data.
As described above, a series of data stream formed so is converted into IR pulse data to be transmitted to the receiving unit of the host system 50. On the other hand, in the case of a pointing device 40, e.g., a mouse, when an user operates the pointing device 40, the position data from the position detection unit 41 and the button data from the button detection unit 42 are transmitted to the microprocessor 20. The position data is divided into horizontal coordinate data and vertical coordinate data, and the button data indicates a press or a release condition of the left or the right buttons on the pointing device 40.
Subsequent processes for the pointing device 40 are performed in a similar manner to the case of the key matrix circuit 10 of the keyboard; and, therefore, a further description thereof will be omitted herein.
Although, in the above data transmission format, the key data may be transmitted as one byte to thereby shorten the data length and enhance the data transmission speed, the prior art device with such format has some drawbacks. Specifically, if, for example, on the keyboard, any character key on the keyboard having two symbolic characters or a combination of one number and one symbolic character is simultaneously pressed together with one or more modifier key(s), such as Shift, Alt, Ctrl, Windows and Application keys, a system scan code for the pressed key becomes identical. That is, the microprocessor 20 in the device first transmits only the press information of the modifier key(s), and then transmits the system scan code for the character key. In such situation, the host system first remembers the press information of the modifier key(s) and determines whether the upper or lower character code on the pressed character key should be generated, based on an incoming system scan code corresponding to the pressed character key.
However, during the transmission of the system scan code to the host system, a loss of the system scan code data may result. For example, system scan code for the modifier key(s) may not get transmitted to the host system, even if the modifier key(s) is pressed. Since the modifier key(s) controls the function of the pressed character key, this situation must be remedied.
It is, therefore, a primary object of this invention to provide a method for transmitting multimedia wireless data to a host system without incurring any loss of data.
In accordance with the present invention, there is provided a method for transmitting multimedia wireless data to a host system, the method comprising the steps of:
(a) generating a key signal corresponding to a selected key;
(b) converting the key signal into a series of data symbols, each of the data symbols having a plurality of chip data, and activating one or more chip data from the plurality of chip data; and
(c) converting each data symbol having the one or more activated chip data into an infrared pulse stream and transmitting it as the multimedia wireless data.